[LLMOps Guide] Beyond PoC to Production-Level LLM Deployment: K8s-Based Optimization and GPU Resource Management Strategies

[LLMOps Guide] Beyond PoC to Production-Level LLM Deployment: K8s-Based Optimization and GPU Resource Management Strategies

The pace of LLM technology has been remarkable. Just a few weeks ago we were still at the PoC (Proof of Concept) stage, calling an API key a few times. Today, LLMs are becoming core features of real services that handle hundreds of concurrent users.

But to be honest, it is all too common for a model that worked fine in a PoC environment to hit unexpected walls once it starts receiving production traffic.

"Latency is too high." "It consumes so much GPU that other services slow down." "When usage spikes, the cost becomes unsustainable."

These problems are exactly the operational complexity we will cover today. Beyond simply deploying a model, you need architecture design that delivers high availability (HA), maximizes cost efficiency, and stably handles large volumes of traffic.

This article dives into the core technology stack and design principles that ML engineers, DevOps engineers, and AI platform architects need to move beyond PoC and build a production-level LLMOps architecture that can handle real business traffic.

1. Why Is LLM Deployment Hard? (The Gap Between PoC and Production)

The difficulty of LLM deployment that we often overlook is not inference itself. The problem sits in serving (operations).

In the PoC stage, we typically test with a simple flow like this: User request -> API Gateway -> Model inference -> Response

In production, every step in this flow can become a bottleneck.

1. Latency: Users expect a response within one second. On top of model inference time, overhead accumulates from receiving the request, queuing it, allocating resources, and sending the response.
2. Cost: GPUs are among the most expensive resources. If you only use 20% of a GPU instead of 100%, the remaining 80% is wasted cost.
3. Scalability: When traffic suddenly increases 10x, you need a mechanism that automatically scales out resources without manual intervention, and scales in when resources are idle.

To meet these requirements, we need to design the architecture around Kubernetes (K8s), the container orchestration tool.

2. Understanding Model Serving Architecture and Analyzing Bottlenecks

LLM inference is not just a sequence of matrix multiplications. There are several physical bottlenecks.

Bottlenecks in the LLM Inference Process

LLM inference is largely a contest among three resources: Compute, Memory Bandwidth, and I/O.

• Compute: The inherent complexity of computing transformer layer weights.
• Memory Bandwidth: This can be the most critical. LLMs must read a huge number of parameters (weights) from memory; if that data transfer is slow, even a high-end GPU becomes bottlenecked.
• I/O: Latency from receiving requests, placing them in a queue, and sending results back out.

Limitations of Conventional Deployment: Inefficiency of Single-GPU Allocation

The most common mistake is assigning an entire model to a single GPU.

# ❌ 비효율적인 예시 (GPU 전체를 점유)
resources:
  limits:
    nvidia.com/gpu: 1  # GPU 1개 전체를 사용한다고 선언

This approach causes resource siloing: even if the model uses only 30% of the GPU, the remaining 70% cannot be used by other services. That is fatal from a cost-efficiency standpoint.

3. Model Orchestration and Resource Isolation with Kubernetes

K8s solves this resource siloing problem and turns model deployment into an automated pipeline.

Overview: Building a Model Deployment Pipeline with K8s

We should treat a model not as a simple Pod but as a service entity. To do that, we typically use the Kubernetes Operator pattern or a Helm Chart to package and deploy model version, scaling policy, and resource requests together.

Practical example: GPU resource requests

When requesting GPU resources, you must expose them as native resources through a Device Plugin.

# ✅ 실무 적용 예시: GPU 리소스 요청 (v1.27+ 기준)
apiVersion: apps/v1
kind: Deployment
metadata:
  name: llm-inference-service
spec:
  template:
    spec:
      containers:
      - name: model-server
        image: your-registry/llm-server:latest
        resources:
          limits:
            # GPU 1개를 요청합니다. (실제로는 파티셔닝을 고려해야 함)
            nvidia.com/gpu: 1
          requests:
            nvidia.com/gpu: 1

The Core of GPU Resource Management: Partitioning and Multi-Model Concurrent Serving (Multi-tenancy)

True optimization starts with splitting the GPU.

1. GPU partitioning (virtualization): You need techniques that use modern GPU architectures (e.g., NVIDIA MIG) or that logically split memory and compute in software so multiple models can share a single GPU. This is the key to maximizing utilization.
2. Multi-tenancy (concurrent multi-model serving): Beyond simply running multiple Pods, the goal is to load and infer multiple independent models (or different versions of the same model) concurrently inside a single GPU instance. This shares GPU memory and the compute pipeline and reduces overhead.

4. Optimization Techniques That Maximize Performance and Cost Efficiency (The Optimization Stack)

Even if you distribute resources well with K8s, it is useless if the model serving engine itself is inefficient. Here we optimize along three axes.

🚀 Inference Engine Comparison: Choose the Right Weapon

Several powerful serving engines exist in the market today. Which one you use depends on your purpose.

Key takeaway: If concurrent request throughput matters most, prioritize vLLM. If you need the most stable and broadest support, start with TGI.

💡 Memory Optimization: Paged Attention and KV Cache

The biggest bottleneck in LLM inference is KV Cache management. For every token you must store the Keys and Values of previous tokens, and this cache consumes a huge amount of memory.

Paged Attention (the core of vLLM): Borrowing the OS virtual-memory concept, it manages the KV Cache in pages. This prevents memory fragmentation and is an innovative technique that lets you serve more requests in the same GPU memory.

🚀 Practical Optimization: Batching and Dynamic Batching

Instead of processing requests strictly in order, you should batch multiple requests and process them together.

• Static Batching: Groups requests into a fixed size.
• Dynamic Batching (Continuous Batching): As soon as a request arrives, resources from completed requests are immediately assigned to other requests. This is the standard for modern LLM serving, and engines such as vLLM implement it.

In short, successful LLM serving is not just loading a model. It is an engineering process of choosing the right inference engine (vLLM/TGI) and maximizing GPU utilization without waste through dynamic batching and Paged Attention.

References: Official Docs

The primary sources for the behavior, configuration, and errors covered in this article are the following official docs. Check them for version-specific options and exact behavior.

• Kubernetes official documentation